How to Open BDM File (INDEX.BDM, MOVIEOBJ.BDM) on Windows & Mac

What is a BDM file?

A BDM file is a binary navigation file written by AVCHD camcorders and cameras that tells a player which recordings exist and how to play them. You will almost always see exactly two of them: INDEX.BDM and MOVIEOBJ.BDM, inside PRIVATE/AVCHD/BDMV on an SD card (or in AVCHD/BDMV on camcorders with a hard drive). They are only a few hundred bytes each.

AVCHD (Advanced Video Coding High Definition) was introduced by Sony and Panasonic in 2006 for consumer camcorders. Its folder layout is derived from the Blu-ray Disc format but uses old-style "8.3" filenames, so Blu-ray's index.bdmv becomes INDEX.BDM and MovieObject.bdmv becomes MOVIEOBJ.BDM. The UK National Archives' PRONOM registry lists both as separate formats, with these fixed signatures at the start of the file:

So when people search how to open BDM file data, the honest answer is that there is nothing to watch inside it. Media players and editors read these files automatically when you open the whole folder; on their own they are useless. The reader above shows exactly what yours contains.

How to open a BDM file (and the video it points to)

Short answer: to open BDM file content the useful way, leave the BDM files where they are and play the .MTS video files in the same folder:

1. Open the card or your copy of it and go to PRIVATE > AVCHD > BDMV. On a Mac, right-click AVCHD and choose Show Package Contents.
2. Open the STREAM folder. Every .MTS file there (00000.MTS, 00001.MTS…) is a video clip.
3. Double-click a clip or open it in VLC media player (free for Windows, Mac and Linux), Windows' built-in player or QuickTime Player.
4. Need MP4? Convert the .MTS with HandBrake (steps below).

Inside the AVCHD folder: what every file is for

An AVCHD card works like a mini Blu-ray Disc: the BDM files at the top point to playlists, the playlists point to clips, and the clips are the video. A player follows this chain from top to bottom:

The .MTS file is an MPEG-2 transport stream made of 192-byte packets: a 4-byte timestamp header plus a standard 188-byte transport packet, as the Library of Congress format description explains. Inside it, AVCHD uses H.264 video with Dolby Digital (AC-3) audio, or uncompressed linear PCM on some professional models. In 2011 the specification added 1080p at 50 and 60 frames per second ("AVCHD Progressive") and 3D. The extension is usually .mts on the camera and .m2ts after some import tools copy it; the Library of Congress quotes Sony Support: there is really no functional difference between the two.

You may also see .TID and .TDT files: PRONOM describes TID as the AVCHD thumbnail index (signature TIDX0100) for the JPEG thumbnails stored in TDT files. Your camera uses them for its preview screen.

Play AVCHD videos on Windows 11 and 10

On Windows you don't open BDM files directly: ignore them and open the .MTS clips; the easiest player is VLC, which plays AVCHD files on Windows, Mac and Linux.

1. Insert the SD card or connect the camera by USB, then open File Explorer.
2. Open PRIVATE\AVCHD\BDMV\STREAM.
3. Right-click a .MTS file > Open with > VLC media player. To watch every clip in a row, select them all and drag them onto VLC.

Windows' own players can often play these clips as well: Microsoft lists .m2ts, the Blu-ray Disc Audio-Video transport stream "commonly used for high definition video on Blu-ray Disc and AVCHD", among the file types Windows Media Player supports. If a clip shows a black screen or no sound, use VLC instead of hunting for codec packs.

To import with dates, album sorting and automatic joining of split clips, Sony recommends its free PlayMemories Home for Windows (the 64-bit version is still offered) and Panasonic offers HD Writer AE 5.4 for its camcorders. See copying without losing dates.

Open BDM files on a Mac (the AVCHD package)

Before you can open BDM file contents on a Mac, you have to find them: macOS shows the AVCHD folder as a single item called AVCHD instead of a folder, which is why many people never see INDEX.BDM or the videos. It's a package, and you can look inside it:

1. In Finder, open the card and go into PRIVATE.
2. Right-click (or Control-click) AVCHD and choose Show Package Contents.
3. Open BDMV > STREAM and open a .MTS file in QuickTime Player or VLC. macOS has played AVCHD natively in QuickTime since OS X Mountain Lion.

Importing to iMovie: Sony says iMovie '08 or later on Mac OS X 10.6.7 or later can import AVCHD, and AVCHD recorded in 50p/60p (PS mode) needs iMovie 10 or later and OS X 10.9. If iMovie doesn't list your clips, drag the .MTS files in from the STREAM folder, or convert them to MP4 first with HandBrake.

PlayMemories Home for Mac no longer works on macOS 10.15 Catalina or later, according to Sony, and no new Mac version is planned, so on a modern Mac use Finder, QuickTime, iMovie or VLC.

iPhone, iPad, Android and Linux

Phones and tablets have no app to open BDM files either, and they don't need one; copy the .MTS clips you want to the device (or open them from the card with a USB-C card reader) and play them in VLC for iOS or VLC for Android. For easy sharing in messaging apps, convert them to MP4 on a computer first.

On Linux, play .MTS files in VLC or mpv. To repackage a clip as MP4 without re-encoding the video, ffmpeg can do it in seconds:

That copies the H.264 video untouched and converts the Dolby Digital audio to AAC, which plays on almost every phone and browser.

Copy camcorder videos to your computer without losing dates

Copy the whole PRIVATE folder (or at least the whole AVCHD folder), not just the .MTS files. Keeping the structure means the BDM, MPL and CPI files stay next to the clips, so editors, players and the maker's software can still read clip order, split recordings and recording dates.

• Why dates get lost: copying a file gives it a new "date modified" on many systems, and some cameras don't store the recording time inside the video at all. MultimediaWiki documents that the Panasonic GH1 writes it only into the .MPL playlist, so a lone .MTS copy loses it. The reader above shows recording dates when it finds them in a playlist.
• Sony: PlayMemories Home for Windows imports AVCHD and can join divided recordings. The 64-bit Windows version is still available (version 6.0.00 is the latest); the 32-bit version was withdrawn in 2020 and the Mac version doesn't run on macOS 10.15 or later.
• Panasonic: HD Writer AE 5.4 supports Windows 11 and 10 for listed camcorder models; the download asks for the 11-character code on the camcorder's battery holder.
• No software? Copy PRIVATE to an external drive as a backup first, then convert the clips you want to MP4. Keep the original folder until you've checked the MP4s.

Convert MTS to MP4 (BDM files can't be converted)

A BDM file has no picture or sound, so converters that try to open BDM file data report an error, and none can turn it into MP4. Convert the .MTS clips it points to instead. HandBrake is a free, open-source video transcoder for Windows, Mac and Linux that outputs MP4, MKV or WebM:

1. Install HandBrake from its official website and open it.
2. Choose Open Source and pick a .MTS file from BDMV/STREAM (or the whole STREAM folder to queue several).
3. Pick a preset such as Fast 1080p30. For interlaced 1080i footage, HandBrake's deinterlace filter removes the comb lines.
4. Check the file name and folder under Save As, then click Start Encode.

Want the original quality with no re-encode? Use the ffmpeg command in the Linux section; it works the same on Windows and Mac. HandBrake doesn't remove copy protection of any kind, so it's meant for your own recordings like these, not commercial Blu-ray Discs.

Can I delete BDM files?

Not on the camera's card, and not one by one. INDEX.BDM and MOVIEOBJ.BDM are what make the clips show up as a recording set. If they are deleted or edited on a computer, the camera, Blu-ray players and import software may no longer show the videos.

• On the card: delete clips with the camera's own delete or format function, which updates the BDM files correctly. Sony's help guides offer Recover Image DB for when "image files were processed on a computer" and the database no longer matches; it repairs the database without deleting images.
• On your computer: keep the BDM files inside the copied folder as long as you keep the .MTS files there. After converting everything to MP4 and checking the result, delete the whole old AVCHD folder at once.
• Are they a virus? No. They are tiny data files with no executable code, created by the camera.

Common BDM and AVCHD problems and fixes

"File format not supported" in Premiere Pro or another editor

You selected INDEX.BDM or MOVIEOBJ.BDM, which "are not video files but auxiliary files", as an Adobe community expert put it. Import the .MTS clips from STREAM, or import the complete AVCHD folder structure (for example through Premiere's Media Browser) so the clips are detected properly.

The AVCHD folder shows only BDMV, or only one "AVCHD" file

That's the normal structure. On Windows, keep going: BDMV > STREAM. On a Mac, AVCHD is a package; use Show Package Contents. If STREAM is empty, your camera recorded in MP4 or XAVC S instead; Sony cameras put those in M4ROOT/CLIP, and still photos are in DCIM.

One recording became several .MTS files

Sony explains that long movies are divided into files of up to 2 GB or 4 GB because of the recording system. The .MPL playlist plays them as one. PlayMemories Home joins them on import if the destination drive is NTFS or exFAT (not FAT32); otherwise play the parts in order, or add them all to one HandBrake or video-editor timeline.

"I copied an AVCHD movie to my computer but I cannot play it"

Sony's answer is to install compatible playback software. In practice, VLC plays every .MTS file. If one specific clip won't play, check it with the tool: a size that doesn't match its .CPI file means the copy was interrupted.

Windows asks "How do you want to open this file?"

Windows has no app registered for .bdm, so when you try to open BDM file icons by double-clicking, it asks you to pick a program. Don't associate .bdm with a video player; close the dialog and open the .MTS files in STREAM instead.

The BDM file is 0 bytes or the tool reports it as damaged

A real INDEX.BDM always begins with INDX0100 and MOVIEOBJ.BDM with MOBJ0100. A zero-byte or garbled file usually comes from an interrupted copy or card error. Copy the folder from the card again; if the card itself is affected, try the camera's Recover Image DB function first. Your clips in STREAM are separate files and are usually still playable.

Related file extensions

If you came here to open BDM file folders from a camcorder, these disc and video formats are organized in a similar way:

Sources and technical references

AVCHD's full specification is licensed and not public, so the format details on this page come from preservation registries, the open-source libbluray parser and the manufacturers' support pages. Checked October 7, 2026.

• PRONOM fmt/1076: AVCHD Index File — .bdm extension, INDX0100 signature (The National Archives, UK).
• PRONOM fmt/1075: AVCHD Movie Object File — MOBJ0100 signature; manages the play order of playlists.
• PRONOM fmt/1074: AVCHD Playlist File and fmt/1054: AVCHD Clip Information File — MPLS and HDMV signatures.
• PRONOM fmt/1077: AVCHD Thumbnail Index File — TIDX0100, .tid/.tdt thumbnails.
• AVCHD — Wikipedia — 2006 introduction by Sony and Panasonic, 8.3 names, directory layout, AVCHD Progressive/3D (2011), QuickTime and VLC support.
• MPEG-2 Transport Stream for Blu-ray Discs (BDAV) and AVCHD — Library of Congress — 192-byte source packets (4-byte TP_extra_header + 188-byte packet); .m2ts/.mts.
• libbluray — VideoLAN — open-source parser whose index_parse.c, mobj_parse.c, mpls_parse.c and clpi_parse.c define the field layout the tool on this page follows.
• MPL — MultimediaWiki — reverse-engineered playlist details, including recording timestamps stored in the .MPL.
• Sony: I copied an AVCHD format movie to my computer but I cannot play it
• Sony: Some of the movies are divided after importing movies to the computer — 2 GB/4 GB division, NTFS/exFAT joining.
• Sony: Can I import movies recorded in AVCHD format using iMovie for Mac?
• Sony PlayMemories Home support and Sony end-of-support notice — Windows 64-bit still available; Mac version not usable on macOS 10.15+.
• Sony Help Guide: Recover Image DB
• Panasonic HD Writer AE 5.4 download — Windows 11 support, camcorder code required.
• File types supported by Windows Media Player — Microsoft Support — .m2ts (BDAV, used for Blu-ray and AVCHD).
• About HandBrake — HandBrake documentation — free, open-source, MP4/MKV/WebM output, no copy-protection circumvention.
• Adobe Community: AVCHD BDMV file format not supported — importing the clips or the folder instead of the BDM files.
• Apple Community: AVCHD file to view on iMac — Show Package Contents > BDMV > STREAM.

Frequently asked questions